1. Field of the Invention
The present invention relates to architectural hardware installed in a door, such as a mortise lock, a tubular lock or other types of lock mechanisms, having a latchbolt retracted by a handle to unlatch the door from a doorframe. More specifically, the present invention relates to architectural hardware in which closely spaced through bolts, located on a bolt circle having a diameter of less than one inch (25.4 mm), extend through a very small opening in the face of the door.
2. Description of Related Art
Current door preparations for architectural hardware of this type require a hole through each face of the door for a spindle and usually an additional two holes on opposite sides of the central spindle hole for through bolting. Alternatively, the spindle hole may be large enough in diameter to accept the through bolts as well.
For a tubular lock (also referred to as a “bored-in” lock), a single, relatively large diameter, central spindle hole may be used. The larger hole accepts the spindle and the through bolts, which pass above and below the tubular lock assembly. The tubular lock assembly is inserted through an opening in the edge of the door.
Through bolts extend through the through bolting holes and also through the mortise lock, or above and below the tubular lock within the door. Through bolting improves the strength and security of the lock installation and may be necessary to make the architectural hardware meet the requirements of the end user and industry specifications.
For decorative purposes in both mortise locks and tubular locks, a rose or escutcheon is required to completely cover the through bolting holes as well as the spindle opening. For conventional designs, the rose or escutcheon must be relatively large in order to cover relatively widely spaced through bolts.
The through bolts generally extend between plates located on opposite faces of the door. A rose or escutcheon of sufficient size is used on each face to cover the opposed plates as well as the through bolts, the spindle holes in the door face and the mounting hardware. The large size of the rose necessary to hide these mounting components detracts from the overall appearance of the door system and is not preferred by architects.